In x-ray imaging, an object of interest to be examined by an X-ray examination apparatus may have a non-constant thickness, in particular in its periphery, i.e. in its boundary area. In mammography and breast tomosynthesis, the patient's breast, i.e. the object of interest, can be compressed between two compression paddles and then scanned using an X-ray source. In the peripheral regions, where the breast does not touch the paddles any more, the X-ray attenuation of the X-rays may be less than in the central region of the object. In order to allow a single grey scale window for viewing, this effect may need to be compensated. For this purpose, so-called peripheral equalization methods may be used.
ULRICH BICK ET AL: “Density Correction of Peripheral Breast Tissue on Digital Mammograms”, RADIOGRAPHICS, vol. 16, no. 6, 1 Nov. 1996, pages 1403-1411, describe an examination apparatus wherein digital mammograms are viewed on video displays. An algorithm has been developed for selective enhancement (i.e. density correction) of the dark peripheral portions of the female breast on mammograms.